This application relates generally to thermodynamic air engines. More specifically, this application relates to controlled motion of a displacer within a thermodynamic air engine.
The use of thermodynamic techniques for converting heat energy into mechanical, electrical, or some other type of energy has a long history. The basic principle by which such techniques function is to provide a large temperature differential across a thermodynamic engine and to convert the heat represented by that temperature differential into a different form of energy. Typically, the heat differential is provided by hydrocarbon combustion, although the use of other techniques is known. Using such systems, power is typically generated with an efficiency of about 30%, although some internal-combustion engines have efficiencies as high as 50% by running at very high temperatures.
Thermodynamic air engines are one class of thermodynamic engine in which a displacer acts to circulate a displacer fluid within a working chamber comprised by the air engine. A specific type of air engine that meets this criterion is a “Stirling engine,” but other types of air engines also share this characteristic.
Throughout industrial history, Stirling engines and other types of air engines have been used for applications, such as pumping water and powering machinery. Recent uses of the Stirling engine have been in electrical power generation. Stirling-engine-powered generators have been installed on submarines as well as on satellites. Portable, external-combustion power-generation units have been produced in quantity. Large-scale solar-heated Stirling cycle power generation units have been shown to produce power reliably on a commercial scale.
While various power-generation techniques exist in the art, there is still a general need for the development of alternative techniques for generating power. For example, while the history of thermodynamic air engines is long, there remain a variety of inefficiencies associated with their operation. There is accordingly still a need in the art for improved methods of operating thermodynamic air engines.